研究了一种维生素A棕榈酸酯(vitamin A palmitate)的合成新途径。实验结果表明,棕榈酸甲酯作为酰基供体,在固定化酶催化下,在无溶剂体系中与维生素A醋酸酯通过酯交换反应生成维生素A棕榈酸酯。对无溶剂体系中催化合成维生素A棕榈酸酯的工艺进行优化,确定的最佳工艺参数为:转速250 r/min;温度60℃;固定化脂肪酶质量分数5%(占反应体系总重);棕榈酸甲酯和维生素A醋酸酯摩尔比1.3∶1。反应到达平衡的时间为3h,转化率为26.93%。此外,研究发现,在反应到达平衡后,连续抽真空,带走反应中产生的醋酸甲酯,反应平衡向产物生成的方向移动,继续反应12 h后,反应转化率可达80%,此时反应液中维生素A棕榈酸酯浓度可高达800 g/L。

It was the first time that vitamin A palmitate was successfully synthesized through catalyzation with immobilized enzyme in solvent-free system. The results showed that the interesterification could take place between vitamin A acetate and methyl palmitate in solvent-free system,wherein the latter was the acyl donors. The conditions for synthesis were optimized as follows: speed was 250 r / min,temperature was 60 ℃,mass fraction of immobilized enzyme was 5%( g / g substrates),molar ratio of methyl palmitate to vitamin A acetate was 1. 3∶ 1. It would take 3h to reach the reaction equilibrium,and the conversion of vitamin A acetate was 26. 93%. In addition,we found that the reaction liquid could possess high ester concentration( 800g / L) and conversion( 80%) if the reaction was carried out in vacuum for another 12h after equilibrium point,.